js-error: _mfInternal is null

If i do sorting within richfaces extendeddatatable component a js error occurs.

A testcase to reproduce this issue is attached.

Steps to reproduce this issue:

1. http://localhost:8080/jsf2testcase/extendeddatatable.jsf
2. click 'Sort ColumnA'
3. js-error occurs

If you use Firefox 9 or chrome 16, everything works as expected. If you use IE8, the following js-error occurs:

IE-8 js-error:
Meldung: 'richfaces.utils.getCSSRule(...).style' ist Null oder kein Objekt
Zeile: 362
Zeichen: 17
Code: 0
URI: http://localhost:8080/jsf2testcase/javax.faces.resource/extendedDataTable.js.jsf;jsessionid=F4E29BC7AFDDEBB4A0395E622B5B44E7?ln=org.richfaces

Meldung: '_mfInternal' ist Null oder kein Objekt
Zeile: 1
Zeichen: 99511
Code: 0
URI: http://localhost:8080/jsf2testcase/javax.faces.resource/jsf.js.jsf;jsessionid=F4E29BC7AFDDEBB4A0395E622B5B44E7?ln=javax.faces

Note: This issue doesn't occur with mojarra-2.1.5
Because of this, i think, that this is a myfaces issue and not a richfaces one.